Topic
Petrochelidon
About: Petrochelidon is a research topic. Over the lifetime, 119 publications have been published within this topic receiving 2684 citations.
Papers published on a yearly basis
Papers
TL;DR: Directional selection gradient analysis showed that measures of skeletal body size and wing length were targets of selection in 1996, and larger birds were favored in the 1996 event, and selection on body size in cliff swallows was more intense than in studies of body size evolution in other bird species.
Abstract: Extreme climatic disturbances provide excellent opportunities to study natural selection in wild populations because they may cause measurable directional shifts in character traits. Insectivorous cliff swallows (Petrochelidon pyrrhonota) in the northern Great Plains must often endure periods of cold weather in late spring that reduce food availability, and if cold spells last four or more days, mortality due to starvation may result. We analyzed morphological shifts associated with viability selection, and how patterns of bilateral symmetry were affected by survival selection, during a four-day period of cold weather in 1992 and a six-day period in 1996 in southwestern Nebraska. Birds that died during the cold were compared to those still alive when the severe weather ended. The event in 1992 killed relatively few birds, but the cold spell in 1996 killed thousands of cliff swallows and reduced their population by about 53%. Climatological records suggest that mortality events comparable to that of 1996 have occurred in only one other year since 1875. Larger birds were favored in the 1996 event. Selection was more intense in 1996 than in 1992 because of more stressful conditions in 1996. Directional selection gradient analysis showed that measures of skeletal body size (tarsus length, culmen width and length) and wing length were targets of selection in 1996. Survivors had lower wing and outer tail asymmetry, and wing and tail asymmetry were targets of selection in both events. Mortality patterns did not differ by sex, but older birds suffered heavier mortality; morphological traits generally did not vary with age. Nonsurvivors were not in poorer apparent condition prior to the weather event than survivors, suggesting that selection acted directly on morphology independent of condition. Selection on body size in cliff swallows was more intense than in studies of body size evolution in other bird species. Larger swallows were probably favored in cold weather due to the thermal advantages of large size and the ability to store more fat. Swallows with low asymmetry were favored probably because low asymmetry in wing and tail made foraging more efficient and less costly, conferring survival advantages during cold weather. This population of cliff swallows may have undergone relatively recent body size evolution.
238 citations
TL;DR: Analysis of how viability selection affected spring arrival time in a migratory Nebraska population found periodic weather-mediated selection against early arrival constrains the cliff swallow’s breeding season and may partly prevent directional selection for earlier nesting.
Abstract: An unusually long period of cold weather in May 1996 caused extensive mortality among insectivo- rous cliff swallows (Petrochelidon pyrrhonota) in the northern and central Great Plains. We analyzed how via- bility selection affected spring arrival time in a migratory Nebraska population by comparing capture histories of survivors with those of birds known to have died and by documenting how arrival time changed in the year fol- lowing the selection event. Surviving birds had signifi- cantly later first-capture dates (an index of arrival time) in the years prior to selection than those that died; a sig- nificant selection differential suggested directional selec- tion for birds that arrived later. Colony sites were occu- pied significantly later following the selection event, and the distribution of first-capture dates in the season after selection was significantly shifted toward later arrivals. Offspring of the survivors tended to arrive later than birds of the same age prior to the selection event. While major weather-caused mortality events of this magnitude are rare in the study area, spells of cold weather severe enough to cause limited mortality are frequent in April and early May. At least 25 probable mortality events of varying severity were identified in the last 50 years based on climatological data. Periodic weather-mediated selection against early arrival constrains the cliff swal- low's breeding season and may partly prevent directional selection for earlier nesting.
184 citations
TL;DR: Cliff swallows probably use conspecific breeding performance in selecting colonies, one component of habitat selection that also includes attraction to Conspecifics and assessment of an individual's own success.
Abstract: Summary
1. One way that animals may select breeding sites is by assessing the reproductive success of conspecifics in one season and settling the next year in those habitat patches where success collectively had been greatest. This sort of habitat assessment may promote the formation of colonies at high quality sites.
2. We examined whether cliff swallows, Petrochelidon pyrrhonota, in south-western Nebraska used conspecific breeding performance to choose colony sites.
3. Reproductive success at colony sites varied spatially within seasons and between seasons, and was autocorrelated at a site from one year to the next, but not over longer time intervals. Cliff swallows thus met the conditions for potential use of information on conspecific breeding performance.
4. Among sites re-used in consecutive years, those with highest collective success in one season showed the greatest rates in colony growth the next season, including the greatest influx of immigrants.
5. The probability of colony-site re-use in successive years increased with collective reproductive success and average breeder body mass (a measure of individual condition) the previous season.
6. Cliff swallows probably use conspecific breeding performance in selecting colonies. This mechanism is one component of habitat selection that also includes attraction to conspecifics and assessment of an individual's own success.
142 citations
TL;DR: The greater likelihood of parasites being introduced into larger colonies by transient birds contributes to an increase in parasite load with increased colony size in Cliff Swallows.
Abstract: While epidemiological models have suggested that the spread of parasites and infectious diseases often depends critically on the extent of movement by infected individuals between populations, there is little empirical information for any organism on the frequency of between-group parasite transmission or how it varies spatially. The trans- mission of parasites between discrete social groups or populations may also help determine a host's total parasite or pathogen exposure. We measured the introduction of parasitic bugs (Oeciacus vicarius) into colonies of Cliff Swallows (Petrochelidon pyrrhonota) by transient birds from outside each group. The transmission of bugs increased strongly as the size of a nesting colony increased. More total transients visited the larger colonies, and the direction of change in transient numbers and the numbers of bugs introduced at a site from week to week tended to vary together. Transients at large colonies were more likely to have pre- viously or subsequently visited other large, infested colonies. The greater likelihood of parasites being introduced into larger colonies by transient birds contributes to an increase in parasite load with increased colony size in Cliff Swallows.
127 citations
TL;DR: The phylogeny of swallows was reconstructed by comparing segments of three genes, nuclear beta-fibrinogen intron 7 (betafib7), mitochondrial cytochrome b (cytb), and mitochondrial ND2, in a variety of combinations using maximum likelihood and Bayesian methods.
119 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 5 |
| 2020 | 2 |
| 2019 | 6 |
| 2018 | 3 |
| 2017 | 3 |
| 2015 | 6 |